Developing compositions used in photographic transfer processes



United States Patent 3,189,448 DEVELOPING COMPOSITIONS USED IN PHOTO- GRAPHIC TRANSFER PROCESSES Frederic R. Bean, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Aug. 22, 1962, Ser. No. 218,550 8 Claims. (CI. 96-48) This invention relates to developing compositions for use in photographic transfer processes and those processes in which such developing compositions are employed. These compositions contain as the major substituents the alkali metal salt of cyclic sulfonic acid, and alkali and a polyethylene glycol.

The reproductions of designs, printed matter, or the like, has been of considerable interest in recent years. One procedure of reproducing designs or printed matter was developed by Henry C. Yutzy and Edward C. Yackel and is described in their US. Patents Nos. 2,596,756, 2,716,059 and 2,592,368. That procedure involved exposing a photographic product consisting of a substantially unhardened light-sensitive gelatino'silver halide emulsion layer on paper or some other support with the emulsion surface in contact with the front of a sheet carrying printed matter or the like, following which the exposed emulsion was subjected to differential hardening by means of a tanning developing agent and treatment with an alkaline solution containing also an activator thereby conditioning the emulsion layer for transfer to a paper sheet such as bond paper upon contact therewith accompanied by pressure.

The activator which has been regarded heretofore as suitable for use in the alkaline developing solution has been a gelatin softener on the order of urea, formamide, ethylene chlorohydrin or sodium nitrate. Occasionally some disadvantage might be encountered with one or the other of these activators and, therefore, it is desired to have an activator available that for any given situation that most suitable for use may be selected.

One object of my invention is to provide a developing composition for photographic transfer processes of excellent stability. Another object of my invention is to provide a developing composition for photographic transfer processes having a better latitude of operation than that of developing compositions for similar purposes available at the present time. A further object of my invention is to provide a developing composition for transfer processes free of deposits or solids formation upon standing and hence readily adapted to be supplied in concentrated form. A still further object of my invention is to provide a developing composition for use in transfer processes which provides better densities of subsequent copies than obtained with developing compositions available at the present time. A still further object of my invention is to provide a photographic transfer process employing as the develop-ing composition therein an aqueous solution, the principal constituents of which are an alkali metal salt of a cyclic sulfonic acid, an alkaline material and a polyethylene glycol.

In its broadcast aspects my invention is based on the finding that compositions of alkaline material, alkali metal salt-s of cyclic sul-fonic acids and certain polyethylene glycols give considerably improved properties of developing compositions available at the present time for photographic transfer processes.

The alkali metal salts of cyclic sulfonic acids which are useful are those which have at least 6 and not more than 18 carbon atoms per molecule. Some acids whose alkali metal salts are useful in this connection are toluene sulfonic acid, xylene sulfonic acid, nitrobenzene 3,189,448 Patented June 15, 1965 ice sulfonic acid, dimethylamino benzene sulfonic acid and the like. The salts of these compounds are used in the developing composition in the proportion of 5-50 grams per liter of solution or 0.5-5% concentration therein. The alkaline material which is employed is an alkali metal carbonate, an alkali metal hydroxide or their mix ture. It is desirable that the developing composition have a pH within the range of 12.5 to 10.5. If the sulfonic acid compound is added in the form of the acid, some of the alkaline material which is added will serve to convert the sulfonic acid to its salt. Ordinarily the alkali will be used in a concentration on the order of 2%.

Also incorporated in the developing composition in accordance with my invention is a polyethylene glycol, any of the polyethylene glycols up to those of 6 carbon atoms being especially useful. This glycol is ordinarily; present in a proportion within the range of l-10% as amounts within this range exhibit optimum propertieswl The preferred range is 25% concentration. Polyethylene glycols which are especially useful are the di, tri, or tetra ethylene glycols. Other additives are sometimes desirable in addition to those which are considered es-; seutial; for instance the use of a sequestering agent is desirable particularly where water having more than a low mineral content is employed, thus overcoming any. eflEect which might be experienced from calcium ion 0ft. the like. Also in some cases, the handling of the developing composition might involve foaming, hence, in; those cases the use of an anti foaming agent, as is well? known in the art, such as a silicone anti-foamer or an; alcohol such as butyl, dodecyl or other water soluble: aliphatic alcohols of at least 4 carbon atoms may be desirable to decrease foaming.

In utilizing the developing composition in accordance with my invention a substantially unhardened light-j sensitve gelatin-silver halide emulsion on a support is; first exposed to a sheet carrying a design or printed ma-tter thereon accompanied by light. The exposed layer is then developed in the presence of a tanning development agent, preferably incorporated in the emulsion layer as described in US. Patent No. 2,592,368. The emulsion is then developed in an aqueous alkaline solution such as a 2% solution of sodium hydroxide and/or sodium carbonate containing the cyclic sulfonic acid which facilitates the transfer of the stratum of the emulsion containing the image to a paper pressed against the developed emulsioni Also present the-rein is the polyethylene glycol which contributes to the stability of the 1 developing solution and improves the ease of transferi and the sensitometric properties of the photographici material. The photographic element containing the emulsion after processing and while still moist is pressed against a paper sheet whereby transfer of the image to said sheet is obtained. I I have noted that the developing composition in accord- 3 ance with my invention is an improvement over developj ing compositions which have been used heretofore for the described purpose. For instance, in the making of subsequent copies I have noted that retained density is? better than in the use of the developing compositions now available. I have found that, because of this retention of density, at least one more usable copy is ordinarily availj able from a given matrix than in the case of develop- 1 mentof the matrix by previously described procedures. I have found that the developing compositions in accordance with my invention operate at a greater pH toler ance and at a greater temperature range than with previous compositions. For instance, with previous developing compositions it has been desirable for good results to limit the pH range to 11.0-10.5. With the developing compositions of the invention a pH range of 12.5-10.5 is tolerated without derogatory effect on the copies obtained. I have found that developing compositions in accordance with my invention are free from deposit or the formation of solid material, particularly of a crystalline nature, upon standing of the composition. Because of this, solutions in which the materials are concentrated can be made up and supplied to customers because of their good stability and the absence of unwanted formations. These compositions are suscetpible to a larger concentration latitude than with conventional developing solutions for transfer processes and in addition the evaporation rate represents a reduction of as much as -40% from that of the conventional solutions.

The following examples illustrate the types of compositions which may be prepared for use in photographic transfer processes in accordance with my invention:

Example 1 A comp-osition was prepared as follows:

Paratolucne sulfon'ic acid grams 17 45% potassium hydroxide in aqueous solution ml 9.5 Potassium carbonate gr-ams 40 'Tetraethylene glycol ml '40 Ethylene diamino tetraacetic acid grams 4.5

Water to make 1 liter.

The potassium hydroxide gave a pH of ll- L.05 in the developing composition. It was found that this developing composition when used in a photographic transfer process gave good sharp copies particularly in the first 3 or 4 copies which were prepared. This composition upon standing was free of any formation of solids material particularly in crystalline form.

, Example 2 80 parts of pa-ratoluene sulfonic acid, 160 par-ts of potassium carbonate, 24 parts of potassium hydroxide and 120 pants of tetraethylenc glycol were dissolved in water to make up 4000 parts of solution. The resulting solution was used as an alkaline developer in a photographic transfer process as described above and copies of printed material of good sharpness were obtained.

Often in alkaline developer solutions it is desirable to include a dye to decrease the passage of light through the solution. Some water soluble dyes especially useful in this connection are:

(1) Direct Deep Black EA concentrate C.F. (color index 582) (2) Nigrosine (color index 865).

(3) Rhodamine BI (color index 749).

The dyes are conveniently employed in a proportion of /21 gram per liter of developer solution.

The following example illustrates developer compositions including dye therein:

Example 3 An alkaline developer solution useful in photographic transfer processes was prepared having the following composition:

Parts Potassium paratoluene sul-fonate 27 Potassium carbonate 40 Tetraethylene glycol Disodium ethylene diamine tetra acetate 4 /2 Direct Deep Black EA co-nc. C.F 0.5

Water to make 1000 parts.

I claim:

1. A composition useful in developing layer-s of unhardened gelatin-silver halide emulsions in a photographic transfer pr-ocess, which essentially consists of an aqueous solution of an alkali metal salt of an aromatic sulfonic acid containing 6-8 carbon atoms per molecule, a polyethylene glycol containing up to 6 carbon atoms per molecule and sufiicient alkaline material to impart a pH of -10.5-12.5 to the solution.

2. A composition useful in developing layers of unhardened gelat n-silver halide emulsions in a photographic transfer process, which essentially consists of an aqueous solution of an alkal-i metal salt of paratoluene sulfonic acid, a polyethylene glycol containing up to 6 carbon atoms per molecule and suflicient alkaline material to impart a pH of 10.5-1'25 to the solution.

3. A composition useful in developing layers of unhardened gelatin-silver halide emulsions in a photographic transfer process, which essentially consists of an alkali metal salt of paratoluene sulfonic acid, a polyethylene glycol containing up to 6 carbon atoms per molecule and sufiicient alkali metal carbonate-containing alkaline material to impart a pH of 10.5-12.5 to the solution.

4. A composition useful in developing layers of unhardened gelatin-silver halide emulsions in a photographic transfer process, which essentially consists of an aqueous solution of an alkali metal salt of paratoluene sulfonic acid, tetraethylene glycol and sufiicient alkali metal carbonate-con-t-aining alkaline material to impart a pH of -125 to the solution.

5. A composition useful in developing layers of unhardened gelatin-silver halide emulsions in a photographic transfer process, which essentially consists of an aqueous solution of an alkali metal salt of paratoluene sulfonic acid, a polyethylene glycol containing up to 6 carbon atoms per molecule and sufiicient alkali metal carbonate and alkali metal hydroxide to impart a pH of 105-125 to the solution.

6. A composition useful in developing layers of unhardened gelatin-silver halide emulsions in a photographic transfer process, which essentially consists of an aqueous solution of potassium para-toluene .sulforrate, tetraethylene glycol and suflicient potassium carbonate-containing alkaline material to impart a pH of 105-125 to the solution.

7. A method of photographic reproduction which comprises exposing an unhardened gelatin-silver halide photosensitive emulsion layer to a two-tone subject, developing in the presence of a tanning developing agent and treating with a composition essentially consisting of an aqueous solution of :an alkali metal salt of paratoluene sulfonic acid, a polyethylene glycol containing up to 6 carbon atoms per molecule and sufiicient alkaline material to impart a pH of l0.5-12.5 to the solution, thereby giving a hardened colloid image and leaving substantially unhardened colloid in the remaining area of the emulsion layer, pressing the emulsion layer while moist against a sheet having an absorbent surface to cause only said unhardened colloid portion of the layer to adhere to said sheet and separating said sheet and said emulsion {layer whereby only 'a stratum of the unhardened colloid portion of said layer is transferred to said sheet.

8. A method of photographic reproduction which cornprises exposing an unhardened gelatin-silver halide photosensitive emulsion layer to a two-tone subject, developing in the presence of a tanning developing agent and treating with an aqueous solution essentially consisting of potassium paratoluene'sulfonate, potassium carbonate, potassium hydroxide and tetraethylene glycol, thereby giving a hardened colloid image and leaving substantially unhardened colloid in the remaining area of the emulsion layer, pressing the emulsion layer while moist against a sheet having an absorbent sun-face to cause only said unhardened colloid portion of the layer to adhere to said sheet and separating said sheet and said emulsion layer 5 6 whereby only a stratum of the unhardened colloid por- 3,042,521 7/62 Demch et a1. 96-66 Lion of said layer is transferred to said shcci. 6 Gra c el ct a1. 9666 References Cited by the Examiner OTHER REFERENCES UN STATES FATENTS 5 The Theory of the Photographic Process," by Mees;

copyright by the MacMillan 00., 1942, p. 361.

2,596,756 5/52 Ymzy a El 96-28 Gl-afkides: Photographic Chemistry, vol. 1, pp. 271-2, 2,716,059 YUtZY Ct 81 Fountain Pmss London, 2,834,676 5/58 Stanley ct a1 96-66 3,017,271 1/62 Piper 96-107 10 NORMAN G.'PORCHIN, Primary Examiner. 

1. A COMPOSITION USEFUL IN DEVELOPING LAYERS OF UNHARDENED GELATIN-SILVER HALIDE EMULSIONS IN A PHOTOGRAPHIC TRANSFER OF AN ALKALI METAL SLAT OF AN AROMATIC SULFONIC ACID CONTAINING 6-8 CARBON ATOMS PER MOLECULE, A POLY ETHYLENE GLYCOL CONTAINING UP TO 6 CARBON ATOMS PER MOLECULE AND SUFFICIENT ALKALINE MATERIAL TO IMPART A PH OF 10.5-12.5 TO THE SOLUTION.
 7. A METHOD OF PHOTOGRAPHIC REPRODUCTION WHICH COMPRISES EXPOSING AN UNHARDENED GELATIN-SILVER HALIDE PHOTOSENSITIVE EMULSION LAYER TO A TWO-TONE SUBJECT, DEVELOPING IN THE PRESENCE OF A TANNING DEVELOPMENT AGENT AND TREATING WITH A COMPOSITION ESSENTIALLY CONSISTING OF AN AQUEOUS SOLUTION OF AN ALKALI METAL SALT OF PARATOLUENE SULFONIC ACID, A POLYETHYLENE GLYCOL CONTAINING UP TO 6 CARBON ATOMS PER MOLECULE AND SUFFICIENT ALKALINE MATERIAL TO IMPART A PH OF 10.5-12.5 TO THE SOLUTION, THEREBY GIVING A HARDENED COLLOID IMAGE AND LEAVING SUBSTANTIALLY UNHARDENED COLLOIID IN THE REMAINING AREA OF THE EMULSION LAYER, PRESSING THE EMULSION LAYER WHILE MOIS T AGAINST A SHEET HAVING AN ABSORBENT SURFACE TO CAUSE ONLY SAID UNHARDENED COLLOID PORTION OF THE LAYER TO ADHERE TO SAID SHEET AND SEPARATING SAID SHEET AND SAID EMULSION LAYER WHEREBY ONLY A STRATUM OF THE UNHARDENED COLLOID PORTION OF SAID LAYER IS TRANSFERRED TO SAID SHEET. 